(a) Field of the Invention
The present invention relates to a display device and a driving device of a light source for the display device.
(b) Description of Related Art
Display devices used for monitors of computers and television sets generally include self-emitting display devices such as organic light emitting displays (OLEDs), vacuum fluorescent displays (VFDs), field emission displays (FEDs), and plasma display panels (PDPs), and non-emitting display devices such as liquid crystal display devices (LCDs) requiring external light source.
An LCD device includes two panels provided with field-generating electrodes and a liquid crystal (LC) layer having dielectric anisotropy disposed between the two panels. The field-generating electrodes are supplied with voltages to generate an electric field across the LC layer, and a light transmittance of the LC layer varies in response to a strength of the electric field, which can be controlled by the voltages supplied. Accordingly, images are displayed by adjusting the voltages supplied.
Light for an LCD device is provided, for example, by an artificial light source provided with the LCD device or by a natural light source. Lamps disposed at the LCD device are an example of the artificial light source. When employing the lamps, a brightness on a screen of the LCD device is usually changed by adjusting a ratio of on and off durations of the lamps or by adjusting a current flowing through the lamps.
The artificial light source, which may be part of a backlight assembly, is often implemented as a plurality of fluorescent lamps such as CCFL (cold cathode fluorescent lamp) and EEFL (external electrode fluorescent lamp) driven by an inverter. The inverter converts a DC voltage into an AC voltage and applies the AC voltage to the lamps to turn the lamps on. The inverter adjusts luminance of the lamps based on a luminance control signal, which is provided to control a luminance of the LCD device. In addition, the inverter controls voltages applied to the lamps based on currents of the lamps.
When the fluorescent lamps are employed as the lamps for the LCD device, the inverter applies a high voltage to the lamps for initial lighting. Thus, if a terminal of the lamp supplied with the high voltage has poor insulation or contact resistance between the terminal of the lamp and a terminal of the inverter, an arc may be generated, which exerts a bad influence on operation of the backlight assembly and may cause a fire in the inverter.
To prevent arc generation, a human inspector inspects a connection state between the lamp and the inverter after manufacturing the inverter. In addition, a separate arc sensing unit may be used, which stops operation of the inverter if an arc is generated.
However, though a manufactured inverter passes a visual inspection by the inspector, the connection state may become poor during subsequent carrying or using of the inverter, thereby creating conditions that allow arc generation. Thus, the arc sensing unit is used to provide continuing protection against arc generation.
Unfortunately, in a conventional arc sensing unit, it is difficult to distinguish between noise components included among normal control signals and arcs. Thus, the conventional arc sensing unit may turn off the lamps in response to the noise components, thereby decreasing a reliability of the inverter.
Therefore, a need exists for a display device that can includes an arc sensing unit able to distinguish between noise and arcs.